Remove trailing whitespace in test suite. Approved by Marshall Clow.

llvm-svn: 271435
diff --git a/libcxx/test/std/experimental/string.view/string.view.access/at.pass.cpp b/libcxx/test/std/experimental/string.view/string.view.access/at.pass.cpp
index af35f54..7ceaf5a 100644
--- a/libcxx/test/std/experimental/string.view/string.view.access/at.pass.cpp
+++ b/libcxx/test/std/experimental/string.view/string.view.access/at.pass.cpp
@@ -36,7 +36,7 @@
     assert ( false );
 #endif
 }
-    
+
 int main () {
     test ( "ABCDE", 5 );
     test ( "a", 1 );